This invention relates to novel polymer product compositions. In particular, it relates to a crosslinked, high modulus, high impact strength, thermoset polymer of dicyclopentadiene units which is formed via a metathesis-catalyst system.
A good thermoset polymer should meet at least two criteria. It should have desirable physical properties and it should lend itself to easy synthesis and forming. Among the most desirable physical properties for many polymers is a combination of high impact strength and high modulus. It is desirable that good impact strength be combined with a modulus of at least about 150,000 psi at ambient temperature. Thermoset polymers with high impact strength and high modulus find useful applications as engineering plastics in such articles of manufacture as automobiles, appliances and sports equipment. Among the critical factors in the synthesis and forming of a thermoset polymer are the conditions and time required to make the polymer set up or gel. Many thermoset polymers require considerable time, elevated temperature and pressure, or additional steps after the reactants are mixed before the setting is complete.
Not only is it desirable that the thermoset polymer have high impact strength, but it is also desirable that it be easily synthesized and formed. A reaction injection molding process achieves this second goal by in-mold polymerization. The process involves the mixing of two or more low viscosity reactive streams. The combined streams are then injected into a mold where they quickly set up into a solid infusible mass. For a reaction injection molding system to be of use with a particular polymer, certain requirements must be met: (1) the individual streams must be stable and must have a reasonable shelf-life under ambient conditions; (2) it must be possible to mix the streams thoroughly without their setting up in the mixing head; (3) when injected into the mold, the materials must set up to a solid system rapidly; and (4) any additives-fillers, stabilizers, pigments, etc., must be added before the material sets up. Therefore, the additives selected must not interfere with the polymerization reaction.
A thermoset homopolymer having high impact strength and high modulus has been described by Klosiewicz in U.S. Pat. No. 4,436,858 and by Leach in U.S. Pat. No. 4,458,037. Characteristics of thermoset polymers include insolubility in common solvents such as gasoline, naphtha, chlorinated hydrocarbons, and aromatics as well as resistance to flow at elevated temperatures.
Work has been done on the metathesis copolymerization of dicyclopentadiene with one or more other monomers to produce soluble copolymers. This copolymer formation has resulted in the production of unwanted insoluble by-products. U.S. Pat. No. 4,002,815, for instance, which teaches the copolymerization of cyclopentene with dicyclopentadiene, describes an insoluble by-product and suggests that the by-product could be a gel of a dicyclopentadiene homopolymer, but does not demonstrate that this is the case.
Some other work, usually in an attempt to produce soluble polymers, has been done on the metathesis polymerization of dicyclopentadiene. Japanese unexamined published patent applications KOKAI Nos. 53-92000 and 53-111399 disclose soluble polymers of dicyclopentadiene. Several syntheses of soluble polymers of dicyclopentadiene have produced insoluble by-products. Takata et al, J. Chem. Soc. Japan Ind. Chem. Sect., 69, 711 (1966), discloses the production of an insoluble polymerized dicyclopentadiene by-product from the Ziegler-Natta catalyzed polymerization of dicyclopentadiene; Oshika et al, Bulletin of the Chemical Society of Japan, discloses the production of an insoluble polymer when dicyclopentadiene is polymerized with WCl.sub.6, AlEt.sub.3 /TiCl.sub.4 or AlEt.sub.3 /MoCO.sub.5 ; and Dall Asta et al, Die Makromolecular Chemie 130, 153 (1969), discloses an insoluble by-product produced when a WCl.sub.6 /AlEt.sub.2 Cl catalyst system is used to form polymerized dicyclopentadiene.
In U.S. Pat. No. 3,627,739 (Devlin), dicyclopentadiene is gelled with unactivated catalyst and then heated for an hour.
Minchak and Minchak et al respectively in U.S. Pat. Nos. 4,002,815 and 4,380,617 each disclose polymerization of cycloolefins to form polymers which may be isolated by precipitation using an alcohol or by steam or hot water stripping. The polymers produced have inherent viscosities from about 0.1 to about 10 and are greater than 90% soluble in solvent. Minchak in U.S. Pat. No. 4,426,502 discloses bulk polymerization of cycloolefins by reaction injection molding in less than about 2 minutes using an organoammonium molybdate or tungstate catalyst.
DeWitt et al in U.S. Pat. No. 4,418,179 discloses impact modification of cycloolefins by polymerization using an organo-ammonium molybdate or tungstate catalyst in less than 2 minutes using reaction injection molding.
Oshika et al in the Bulletin of the Chemical Society of Japan, line 41, pages 211-217 (1968) discloses ring opening polymerization of norbornene and its derivatives by MoCl.sub.5, WCl.sub.6 and ReCl.sub.5 catalysts. Dark crude polymer is obtained which is dissolved and reprecipitated with methanol.
U.S. Pat. No. 4,002,815 discloses the use of a metathesis-catalyst system which employs a dialkylaluminum iodide, an alkylaluminum diiodide or a mixture of trialkylaluminum compounds with elemental iodine to produce substantially gel-free copolymers of cyclopentene and dicyclopentadiene.
U.S. Pat. No. 4,069,376 discloses the use of a three component catalyst comprised of a soluble tungsten compound, a dialkylaluminum chloride or alkylaluminum dichloride, and a dialkylaluminum iodide or alkylaluminum diiodide to produce substantially gel-free norbornene-dicyclopentadiene copolymers.
U.S. Pat. No. 4,535,097 discloses a cellular crosslinked poly(dicyclopentadiene) which is made with a metathesis-catalyst system. The cellular polymer is made by injecting the catalyst system, which includes an alkylaluminum activator, into a reaction vessel which is preheated, preferably to a temperature from about 100.degree. to about 125.degree. C.